Crossword Genius

Source of petroleum as strand is developed (3,5)

Ross

I believe the answer is:

tar sands

'source of petroleum' is the definition.
(sand containing petroleum)

'as strand is developed' is the wordplay.
'is developed' indicates anagramming the letters.
'as'+'strand'='asstrand'
'asstrand' anagrammed gives 'TAR SANDS'.

I've seen this clue in The Guardian.
Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.